1. Field of the Invention
The present invention relates to non-contact transformers, more specifically, to non-contact transformers each of which is mounted around the shaft of a steering wheel portion of a four-wheel automobile and performs power supply and signal transmission in the handle portion as well as to a vehicular signal relay apparatus using such a non-contact transformer.
2. Description of the Related Art
At present time, automobiles are spread all over the world. There are many kinds of automobiles having an air-conditioner and a cruise control apparatus. The manipulation system of most of the electric system of such equipment is concentrated near the front panel and the base of the steering wheel. Therefore, to manipulate such an electric system, the driver needs to take one of his hands off the steering wheel though temporarily, which may cause an erroneous steering wheel manipulation and possibly a serious accident during high-speed driving etc.
To cope with the above problem, safety-oriented four-wheel automobiles are spreading in which control switches of an electric system is provided in a steering wheel portion and the driver need not take his hands off the steering wheel even during manipulation. In this case, exchange of electricity with the manipulation system in the steering wheel portion is performed in a wired manner and flexible wires having resilience are used to prevent disconnection by steering wheel rotation manipulations.
However, in the above wired electric system, attachment of flexible wires is very laborious work because the wires need to be located at neutral positions to assure uniform rightward and leftward steering wheel rotation manipulations.
Since the wires rub against each other during steering wheel manipulations, the product life is short. Further, Some users insist that sound of rubbing between the wires and slight resistance that occurs during manipulations make driving less comfortable.
The inventors attempted to solve the above problems by employing, instead of wired ones, electromagnetic induction type power supply and signal transmission using a non-contact transformer having a ferrite core. However, manufacture of such an electric system was difficult because the core was large and hence was warped during sintering.
It is an object of the present invention to provide a non-contact transformer which simplifies attachment work and causes no sound of rubbing between wires or resistance during steering wheel manipulations.
It is another object of the invention is to provide a non-contact transformer which can increase the transmission efficiency as well as can be manufactured easily by virtue of a minimized warp of a core that occurs during its manufacture.
It is still another object of the invention to provide a non-contact transformer which is free of such problems as cracking during assembling work and hence can greatly facilitate the assembling work.
It is yet another object of the invention to provide a non-contact transformer which suppresses adverse effects of external noise waves on signal transmission and thereby provides high stability of signal transmission.
It is a further object of the invention to provide a vehicular signal relay apparatus having any of the above non-contact transformers in a steering wheel portion.
According to a first aspect of the invention, there is provided a vehicular signal relay apparatus in which a non-contact transformer is accommodated in a steering wheel portion of a vehicle to relay an electric signal or power. The non-contact transformer comprises a winding of wire, two disc-shaped magnetic cores each having at least one concentric groove in which the winding is accommodated, and at least one magnetic sleeve that covers at least outer circumferences of the two magnetic cores. In the aspect of the present invention, the two magnetic cores are opposed to each other with a predetermined interval with a space interposed in between that is enclosed by the magnetic sleeve.
According to another aspect of the invention, there is provided a non-contact transformer which comprises a winding of wire, two disc-shaped magnetic cores each having at least one concentric groove in which the winding is accommodated, and at least one magnetic sleeve that covers at least outer circumferences of the two magnetic cores, where the two magnetic cores are opposed to each other with a predetermined interval with a space interposed in between that is enclosed by the magnetic sleeve.